In the construction and design of certain types of electrophotographic printers, such as Hewlett Packard's widely acclaimed series of LaserJet.TM. printers, it has been a common practice to use a fixedly mounted disposable print cartridge adjacent to the paper path within the printer housing, and load paper into a paper cassette which is located a certain distance beneath the print cartridge. This design constraint is present in order to allow a D-shaped pick roller to be operated between a stack of paper within the paper cassette and a paper guide for passing the paper to the print area of the print cartridge. During this operation, the D-shaped pick roller rotates to drive the top sheet of paper within the paper stack between a photoconductive drum of the print cartridge and an adjacent transfer roller, as is well known in the electrophotographic printing arts.
Whereas the above paper transport mechanism operates highly satisfactorily in many respects, there are certain disadvantages associated with the cost, maintenance, and space requirements occasioned by the use of the D-shaped pick roller. It is the elimination of these disadvantages to which the present invention is directed.